Piston pump



FIG. 1 is a left side view of the piston pump of my design;

FIG. 2 is a front view thereof;

FIG. 3 is a right side view thereof;

FIG. 4 is a rear view thereof;

FIG. 5 is a top view thereof;

FIG. 6 is a bottom view thereof;

FIG. 7 is a front-left perspective view thereof;

FIG. 8 is a rear-left perspective view thereof;

FIG. 9 is a rear-right perspective view thereof; and,

FIG. 10 is a front-right perspective view thereof.

In the drawings, the broken lines depict unclaimed subject matter only and form no part of the claimed design. 

CLAIM The ornamental design for piston pump, as shown and described. 